kitten/include/arch-x86_64/tsc.h

   1 /*
   2  * linux/include/asm-i386/tsc.h
   3  *
   4  * i386 TSC related functions
   5  */
   6 #ifndef _ARCH_x86_64_TSC_H
   7 #define _ARCH_x86_64_TSC_H
   8
   9 #include <lwk/types.h>
  10 #include <arch/processor.h>
  11
  12 typedef uint64_t cycles_t;
  13
  14 /**
  15  * Returns the current value of the CPU's cycle counter.
  16  *
  17  * NOTE: This is not serializing. It doesn't necessarily wait for previous
  18  *       instructions to complete before reading the cycle counter. Also,
  19  *       subsequent instructions could potentially begin execution before
  20  *       the cycle counter is read.
  21  */
  22 static __always_inline cycles_t
  23 get_cycles(void)
  24 {
  25         cycles_t ret = 0;
  26         rdtscll(ret);
  27         return ret;
  28 }
  29
  30 /**
  31  * This is a synchronizing version of get_cycles(). It ensures that all
  32  * previous instructions have completed before reading the cycle counter.
  33  */
  34 static __always_inline cycles_t
  35 get_cycles_sync(void)
  36 {
  37         sync_core();
  38         return get_cycles();
  39 }
  40
  41 #endif